How do you solve #9- 3x = 21#?

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Answer 1 · 2017-05-16T21:51:53

See a solution process below:

First, subtract #color(red)(9)# from each side of the equation to isolate the #x# term while keeping the equation balanced:

#-color(red)(9) + 9 - 3x = -color(red)(9) + 21#

#0 - 3x = 12#

#-3x = 12#

Now, divide each side of the equation by #color(red)(-3)# to solve for #x# while keeping the equation balanced:

#(-3x)/color(red)(-3) = 12/color(red)(-3)#

#(color(red)(cancel(color(black)(-3)))x)/cancel(color(red)(-3)) = -4#

#x = -4#